Operating mechanism for vacuum circuit breaker including contact pressure springs

ABSTRACT

A circuit breaker contains a pair of series-connected vacuum interrupter units which are coaxial with one another and spaced from one another. An operating mechanism is disposed between the vacuum interrupters, and is operated by an operating linkage moving along a line perpendicular to the axes of the vacuum interrupters. The operating linkage includes a toggle-type mechanism between the bottles which is expanded and contracted by the movement of the operating rod in order to operate the vacuum interrupter contacts simultaneously. A pair of conductive links used to connect the interrupters in series are used as parallelogram links for the operating toggle mechanism links. Contact loading springs are placed mechanically between the ends of the toggle links and the vacuum interrupter bottles. The contact spring forces are adjustable by the use of shims between the preloading springs and their spring carriers.

United States Patent [191 Netzel OPERATING MECHANISM FOR I VACUUMCIRCUIT BREAKER INCLUDING CONTACT PRESSURE SPRINGS [75 inventor: PhilipC. Nctzel, Milmont Park, Pa.

[73] Assignee: I-T-E Imperial Corporation,

I Philadelphia, Pa. [22] Filed: Oct. 26, 1971 [21] Appl. No.: 192,029

[52] US. Cl. ..200/l53 V, 200/144 B, 200/82 B, ZOO/153 H [51] Int. Cl...H0lh 3/00 [58] Field of Search ..200/l44 R, 153 S, 200/153 V, 153 G,153 H, 82 R, 82 A, 82 B, 144 B [56] References Cited UNITED STATESPATENTS 3,4l8,439 12/1968 Casey et al ..200/153 V UX 1,764,401 6/l930Griswold ..200/l53 V UX 3,433,913 3/1969 Leeds ..200/l53 V UX e ii I: L'11 r c u w e 1,1, Ll

[451 Apr. 17, 1973 3,597,556 8/1971 Sharp et al ..200/l44 B PrimaryExaminer-J. R. Scott Att0rneyOstrolenk, Faber, Gerb & Soffen [5 7ABSTRACT A circuit breaker contains a pair of series-connected vacuuminterrupter units which are coaxial with one another and spaced from oneanother. An operating mechanism is disposed between the vacuuminterrupters, and is operated by an operating linkage moving along aline perpendicular to the axes of the vacuum interrupters. The operatinglinkage includes a toggletype mechanism between the bottles which isexpanded and contracted by the movement of the operating rod in order tooperate the vacuum interrupter contacts simultaneously. A pair ofconductive links used to connect the interrupters in series are used asparallelogram links for the operating toggle mechanism links. Contactloading springs are placed mechanically between the ends of the togglelinks and the vacuum interrupter bottles. The contact spring forces areadjustable by the use of shims between the preloading springs and theirspring carriers.

6 Claims, 7 Drawing Figures 516 1 L rAuc/r PATENTED 3.728.508

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if /3 3% I 23/ PATENTEDAPR 1 71973 SHEET 2 UF 4 INVENTOR. fay/A A 6'.fiflffl.

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OPERATING MECHANISM FOR VACUUM CIRCUIT BREAKER INCLUDING CONTACTPRESSURE SPRINGS RELATED APPLICATIONS This application is related tocopending application Ser. No. 192,073, filed Oct. 26, 1971, entitledLow Profile Circuit Breaker With Staggered Terminals, in the name ofThomas F. Brandt, J r., et al. assigned to the assignee of the presentinvention.

BACKGROUND OF THE INVENTION This invention relates to an operatingmechanism for vacuum circuit breakers, and more specifically relates toa novel spring toggle arrangement for simultaneously operating themovable contacts of two vacuum interrupters which are axially spacedfrom one another and which are disposed coaxially.

In order to use vacuum interrupters for medium high voltage circuitbreakers, for example, circuit breakers rated at 34.5 kilovolts or 38kilovolts, it is necessary to provide two presently available vacuuminterrupters in series with one another. That is, an economical singlevacuum interrupter bottle which can operate at these medium voltages isnot available. These two vacuum interrupter units may conveniently belocated coaxially with respect to one another and spaced from oneanother so that an operating mechanism can be positioned between thevacuum bottles. By placing the operating mechanism between the vacuumbottles, the contact pressures present in each interrupter when closedwill be arranged to oppose one another.

Arrangements of this type are generally disclosed in US. Pat. No.3,597,556 to Sharp, where the operating mechanism of that patent isdisposed between two spaced vacuum bottles, but where, however, themechanism is arranged to cause the contacts in the interrupter to have awiping action.

BRIEF SUMMARY OF THE INVENTION The principle of the present invention isto provide a novel and modified operating mechanism for two spacedvacuum interrupters which are connected in series such that contactbiasing forces are provided in a direction parallel to the axis of thebottles, with a toggle mechanism automatically preloading the contactsat the time the contacts touch. The mechanism is further provided suchthat when the contact erosion reaches its half-life, the spring forcewill be equal to the recommended momentary contact loading force. Thetoggle mechanism is further arranged so that it cooperates withcurrent-carrying linkages which connect the two interrupters in serieswith one another and which bypass current around the operatingmechanism.

M'ore specifically, and in accordance with the invention, novel contactloading springs are provided for the operating mechanism of a pair ofvacuum interrupters which are so arranged that they will hold theinterrupter contacts closed against the magnetic forces generated bylarge momentary fault currents.

The mechanism also provides compensation for contact erosion of thecontacts within the interrupter bottles. Thus, the contact loadingsprings are preloaded to about 75 percent of their required force forfull momentary rating at the position where the contacts of the vacuuminterrupters meet. As the toggle is further operated, the force on thecontacts due to the springs builds up to a maximum of about 112.5percent when the toggle is in its fully extended position. As thecontacts erode due to interruption duty, this maximum force willgradually decrease. At the point where the contacts have reached theirhalf-life (0.0625 inch erosion for a typical commercially availablevacuum interrupter), the maximum spring force will be equal to therecommended momentary contact loading.

The contact spring carriage can, at this point, be adjusted by loadingshims between the springs and the contact spring carriage to restore thedesired contact spring force.

It will be noted that the use of a toggle linkage for operating thecontacts permits the circuit breaker operating mechanism to be reducedin size as compared to an arrangement in which the contacts are operatedin tandem, since the forces required from the operating mechanism tohold the contacts closed are reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustratesportions of the mechanism used in accordance with the present invention.

FIG. 2 schematically illustrates the toggle mechanism of FIG. 1 with themechanism components shown in their open position.

FIG. 3 is similar to FIG. 2, but shows the toggle components in theircontact closed position.

FIG. 4 shows a cross-sectional view of a novel arrangement for theopening spring of the operating mechanism of FIG. 1.

FIG. 5 is a plan view, partially in cross-section, of one detailedembodiment of the invention.

FIG. 6 is a cross-sectional view of FIG. 5, .taken across the sectionline 6 6 in FIG. 5.

FIG. 7 is a perspective view, partially exploded, illustrating thetoggle operating mechanism of FIGS. 5 and 6.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIGS. 1, 2 and3, there is schematically illustrated a circuit breaker mounted on atruck 10 which can be racked between various positions in a conventionalmanner, where the truck 10 carries a main operating mechanism 11 whichmoves a shaft 12 with vertical motion which is transmitted to a togglelinkage 13. The toggle linkage 13 is then connected at one end to shaft14 and at its other end to shaft 15, where the shafts 14 and 15 are, inturn, connected to the movable contacts of vacuum interrupters l6 and 17respectively. Each of vacuum interrupters 16 and 17 and'the togglemechanism 13 are mounted on truck 10 through the insulator posts 18 and19.

Interrupters 16 and 17 then have outer terminals 20 and'21 respectively,where terminal 20-is connected to a primary disconnect contact 22, whileterminal 21 is connected to a conductor bar 23. The conductor bar 23 isthen, in turn, connected to a suitably supported primary disconnectcontact 24.

It will be understood that FIG. 1 schematically illustrates only asingle pole of a circuit breaker which, conventionally, would be amulti-pole unit.

The vacuum interrupters 16 and 17 are so arranged that when theoperating shaft 12 is in the upper position shown in FIGS. 1 and 2, theends of toggle links 30 and 31 will be moved to their collapsedposition, so that the members 14 and 15 will be retracted relative tovacuum interrupters 16 and 17 respectively, and the vacuum interruptercontacts will be open. In order to close the vacuum interruptercontacts, shaft 12 is moved downwardly by the mechanism 11, which willbe later described, so that links and 31 spread away from one another inorder to move members 14 and 15 toward their respective interrupters 16and 17, thereby to close the vacuum interrupter contacts of eachinterrupter 16 and 17.

FIG. 3 shows the toggle links 30 and 31 in their contact closed positionafter having moved through the closing stroke indicated in FIG. 2. Inone embodiment of the invention, where the vacuum interrupters 16 and 17are of the type manufactured by the General Electric Company as theirtype No. PV-O3G, this total closing stroke will be 0.75 inch for eachvacuum interrupter.

In order to insure an approximate linear motion for members 14 and 15,connected to toggle links 30 and 31, guide links 32 and 33 are pivotallymounted to the lower ends of links 30 and 31 respectively, and arefurther pivotally supported from the upper stationary mounting structure34. The pin 35 which connects links 30 and 31 is further guided in asuitable guide slot 36 to insure that the center of the toggle formed bylinks 30 and 31 moves only vertically and in the direction of movementof shaft 12.

As shown in FIGS. 2 and 3, and as will be described more fullyhereinafter, the support member 34 may also be a conductive member whichis electrically connected to pivot links 40 and 41, which are, in turn,electrically connected to the terminals of interrupters 16 and 17,connecting the members 14 and 1S respectively.

In accordance with an important feature of the invention, a contactloading spring, schematically illustrated in FIGS. 1 and 2 as spring 42,is connected between the end of shaft 12 and the shaft pin 35 of thetoggle, including links 30 and 31. This will then provide the desiredcontact loading by forces exerted through pivot pin 35 when the contactsare in their closed position.

The operating mechanism 11 of FIG. ll includes a jackshaft which has acrank 51 extending therefrom for each pole of the breaker. Shaft 51,shown in FIG. 1, is connected to the bottom of shaft 12 and is furtherconnected to an opening spring mechanism 52, which will be shown in moredetail in connection with FIG. 4. When the interrupters are in theirclosed position (FIG. 3), the mechanism 11 is latched against motion dueto opening spring 52 by the latch system including latch 53, crank 54which rotates about fixed pivot 55, and link 56 connected to crank 51.Thus, in the closed position, the right hand end of crank 54 will belatched under latch 53. In order to open the breaker, latch 53 isremoved so that crank 54 can rotate counterclockwise about shaft 55,thereby allowing opening spring 52 to move the shaft 12 upwardly fromthe position of FIG. 3 to the position of FIG. 2.

A closing spring is provided to close the breaker contacts and theclosing spring 60 is provided with an output shaft 61 pivotally mountedon rotatable latch plate 62, which has a latching detent which can belatched by the latch 63. Plate 62 is then provided with a cammingsurface 62a which cams against a roller 64 at the left-hand end of crankarm 54. Thus, when the latch 63 is moved to an unlatched position, as bythe operation of a closing coil, the plate 62 is rotated due to theexpanding action of closing spring 60 so that cam surface 62a, actingagainst roller 64, rapidly rotates crank 54 around shaft 55, therebyrotating crank 51 clockwise to move shaft 12 downwardly. Note that atthe end of this operation, latch 53 reseats itself against the roller54a at the right-hand end of crank 54.

The downward movement of shaft 12 causes the downward motion of pin 35,and thus the closing of the contacts, as shown in FIG. 3. Note that inmoving to this fully expanded toggle position, that the spring 42 (FIGS.1 and 2) will compress, thereby to place a spring loading force on theclosed contacts. Thus, even though the contacts may erode, there will besufficient force remaining in the precompression of the spring 42 tocreate the necessary contact pressure for the contacts within theinterrupters 16 and 17. Moreover, this force may be easily adjusted, forexample, by loading shims between the spring and its carrier, or in thecase of FIG. 2, by threading the nut 65 downwardly on shaft 12, therebyto move spring containing washer 66 toward shoulder 67, which containsthe lower end of spring 42.

One important feature of the present invention is in the construction ofthe opening spring 52, which provides a buffering dashpot to absorb theexcess energy during the opening operation of the interrupters. Thus, inFIG. 4, the crank arm 51 connected to shaft 12, rotates counterclockwisein order to open the breaker. The opening springs shown as concentricsprings 70 and 71 are contained within opening spring housing 72, whichcontains a movable plate on piston 73 which is secured to a link 74,which is connected to shaft 12 and crank arm 51. In addition, the link74 is further connected to a shaft 75 having an enlarged head 76, whichmoves within a cavity 77 of the spring housing. Thus, during the openingoperation, shaft 12 can move rapidly under the expanded force of springs70 and 71, until the piston 73 passes port 78, at which time theincrease in pressure on the right-hand surface of piston 73 is raised,thereby providing a strong restraining action against the continuedopening movement of shaft 12. At the same time, the movement of enlargedhead 76 into the chamber 77 exerts a controlled restraining forceagainst too rapid movement of shaft 12 in the opening direction.

FIGS. 5, 6 and 7 illustrate one specific embodiment of one pole of a34.5 kilovolt circuit breaker which uses the toggle mechanism of thepresent invention.

The overall breaker is best seen from FIG. 5, which shows supportmolding structures and 101, which serve to support vacuum interrupterbottles 102 and 103 respectively. A terminal bushing 104, having aprimary disconnect contact 105 at the end thereof, is connected to thefixed contact terminal of vacuum bottle 102.

An electrical conductor bar 106 is connected to the fixed contactterminal of vacuum bottle 103, and the conductor bar 106 isappropriately connected to a suitably supported bushing 107, having thesecond primary disconnect contact 108 at the end thereof. Note that theprimary disconnect contacts 105 and 108- are not disposed above oneanother, but are staggered in position in order to permit a low profilefor the breaker. That is, a given dielectric spacing is obtained betweenterminals 105 and 108, where this spacing is not a complete verticalspacing, as was the case in the prior art. Consequently, the breaker canbe mounted in an outdoor cubicle having a height less than about 6 feet,which can conveniently be shielded or hidden by common shrubbery toproduce an unimposing appearance for the substation using theswitchgear.

Thus, the overall breaker will have a shorter profile than it would havehad if the breaker terminals were disposed above one another in theconventional manner. This is the subject matter of the invention claimedin copending application Ser. No. 192,073.

FIGS. 5 and 6 also show the operating shaft 110 which corresponds to theoperating shaft 12 of FIGS. 1 to 4, where the operating shaft 110 movesin the direction of arrow 111 to open the contacts of vacuuminterrupters 102 and 103, and moves in the direction of arrow 112 toclose the interrupter contacts.

The operating mechanism for operating the interrupters 102 and 103 isdriven from shaft 110 and is generally supported and sub-assembled onthe conductive block 120 (FIGS. 5 and 7). The block 120 is, in turn,secured on a top cover plate 121 by bolts 122 and 123 in FIG. 5, whichthread into the top of conductive member 120. The cover plate is notshown fully in detail, but is made sufficiently wide to cover the top ofthe operating mechanism.

The top cover 121 is then connected to suitable side plates 124 and125', which are, in turn, connected to the support moldings 100 and 101,and are disposed adjacent the vacuum interrupter bottles 102 and 103.

A generally L-shaped slide guide plate 126 has a flange at its upper endbolted to the top cover 121 by the bolts 127 and 128 (FIG. 5). Guideplate 126 then has an elongated guide opening 129 therein (FIGS. 5 and7) which opening receives and guides the motion of pivot shaft 130.

The upper end ofa shaft portion 131 (FIGS. 5 and 6) which is adjustablyconnected to the main operating shaft 112, has a cylindrical bushing 132connected to the end thereof which slidably receives the pivot pin orshaft 130. The pivot pin 130 is then connected to the toggle link pairs133-134 and 135-136 respectively. These toggle link pairs correspondgenerally to the toggle links 31 and 30 respectively in FIGS. 1 to 4.Note that these links are separated from one another by the bushing 132on the pin 130, and further note in FIG. 6, that these links may be bentto accommodate themselves to a relatively small volume.

The opposite ends of links 133 and 134 are then pivotally connected totoggle links 137 and 138 through the pin 139, while the outer ends oflinks 135 and 136 are similarly connected to toggle links 140 and 141,which are carried on pin 142. The upper end of the pairs of links 137and 138 are pivotally connected to the conductive support 120 by the pin143 (FIGS. 5

and 7), while the upper ends of links 140 and 141 are pivotallyconnected to support 120 by the pin 144.

Each of pins 139 and 142 are surrounded by bushing members which haveextensions -151 and 152-153 extending therefrom. These extensions arespring guide pins which respectively receive contact pressure springs154 to 157 respectively. The opposite ends of contact pressure springs154 and 155 then bear against a spring carrier plate 158 and, similarly,springs 156 and 157 press against a spring carrier plate 159. The springcarrier plates 158 and 159 then receive contact clamps l60'and 161 whichclamp onto the movable contact terminals 162 and 163 respectively ofvacuum interrupters 103 and 102 respectively, Note that the clamps 160and 161 are conventional split member clamps which are tightened on thecylindrical contact terminals 162 and 163 respectively by tightening theclamping bolts. The spring carriers 158 and 159 are then firmly securedto the terminals 162 and 163 respectively, by the bolts and 171respectively, which extend through the center of the spring carriers 158and 159 respectively, and into the ends of terminals 162 and 163respectively.

The upper ends of clamp members 160 and 161 then have extending tongues175 and 176, which tongues contain openings which receive suitable pinssuch as pins and 181, which are used to form an electrical connectionpermitting mechanical rotation between the clamps 160 and 161 and theelectrical connecting links -191 and 192-193. The upper ends of links190 to 193 are also in-rotatable pressure contact with the mainconductive support body 120 by a suitable pressure connection whichincludes shafts 194 and 195 respectively (FIGS. 5 and 7 Thus, the links190 and 191 form an electrical connection from the terminal 162 ofvacuum interrupter 103 to the conductive support 120. The links 192 and193 then continue this electrical connection from the body 120 to theterminal 163 of interrupter 102.

It should be noted that links 190-193 take all of the electricalconducting duty involved in the series connection of interrupters 102and 103, and remove the need for electrical conduction through portionsof the main operating mechanism. It will further be noted that theselinks also act to force movement of members 162 and 163 of interrupters103 and 102 respectively to be constrained to a straight line so thatpure butt contacting action is obtained within the vacuum interrupterunits.

It will finally be observed that there is intentional free play betweenthe end cap nuts 200-201 and 202-203, which are secured to the ends ofposts 150-153 respectively, and serve as a stop for the movement of thespring brackets 158 and 159. As will be seen more fully hereinafter,this intentional free play improves the operation of the unit duringopening, since it permits the application of an impact force to theclosed contacts.

The operating mechanism of FIGS. 5, 6 and 7 is shown with theinterrupter contacts in their closed position. It will be noted that theforces of springs 154 through 157 (which serve the purpose of spring 42in FIGS. 1, 2 and 3) press the spring carriers 158 and 159 outwardly andaway from one another, thereby to press the movable contact terminals162 and 163 of interrupters 103 and 102 respectively toward theircontact engaged position. Note further that the contact biasing force isaxially directed in the same direction in which the contacts wouldnormally move. It will also be seen that the breaker can be held in itsclosed position through the toggle mechanism with the application ofrelatively small forces to the shaft 110.

The operating mechanism is so adjusted that when the toggle is in itsfully extended position, as shown in FIGS. and 6, the force on thecontacts is about 1 12.5 percent of the rated force. Thus, when thecontacts erode due to interruption, so that the spring carriers 158 and159 will be further apart when the breaker contacts are closed, thereduction in spring force will be to the 100 percent figure after thecontacts have eroded by their half-life, which would conventionally beabout 0.0625 inch. This force can then be easily adjusted by thelocation of shims in the toggle mechanism. Thus, in FIGS. 5 and 6, thereare shown shims 210 and 211 disposed between spring carriers 158 and 159and the terminal members 162 and 163 respectively.

It is important to note that the use of these shims does not affect thestroke of the operating mechanism, but merely change the end position ofthe movable contacts.

In order to open the interrupter, shaft 110 moves upwardly in thedirection of arrow 111, with the shaft being guided for linear movementby the guide slot 129, which receives pin 130. The upward movement ofpin 130 causes toggle links 133-134 and 135-136 to move inwardly. Oncethey have reached a given position, the nuts 200 to 203 on the springguide pins 150-153 respectively, strike their respective spring carriers158 and 159. This impact force is then applied to the contacts ofinterrupters 102 and 103 in order to break any welds that may have beenformed between these contacts, and the continued movement of pin 130upwardly causes the continued relative inward movement of theinterrupter contacts, moving them to their disengaged positions.

During this movement, guide links 137 and 138, and 140-141 moverespectively clockwise and counterclockwise, and similarly, the links190-191 and 192-193 execute the same movement. Thus, these various pairsof links form two parallelograms causing the brackets 160 and 161 tomove generally linearly, without rotation. Thus, good straight-lineaction is obtained for the movement of the movable contacts ofinterrupters 102 and 103. Note further that this novel action isobtained by incorporating the links 190-193, which are used primarily toform the electrical conducting path through the series connectedinterrupters, in the mechanical toggle mechanism.

In order to reclose the interrupters, the operating shaft 110 is moveddownwardly in the direction of arrow 112 and the toggle mechanismresponds accordingly by extending between the pins 139 and 142. Themechanism is so adjusted that at the instant the contacts touch, thecontact loading springs are preloaded to about 75 percent of therequired force for full momentary rating. As the toggle is furtheroperated, this force on the contacts builds up to its predescribedmaximum of 112.5 percent when the toggle has been fully extended.

Although there has been described a preferred embodiment of this novelinvention, many variations and modifications will now be apparent tothose skilled in the art. Therefore, this invention is to be limited,not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:

1. An operating mechanism for first and second vacuum interrupters; saidfirst and second vacuum interrupters each including generallycylindrical housings having axially disposed and axially movable contactterminal members extending from one end surface thereof; and means forsupporting said first and second vacuum interrupters in spaced coaxialrelation with said one end surfaces facing one another; said operatingmechanism comprising, in combination:

an axially movable operating shaft movable generally perpendicular tothe axes of said first and second interrupters;

first and second toggle link means, each having first and second ends,and pivotally connected at their said first ends to one another and tosaid operating shaft;

first and second guide link means for guiding the motion of said secondends of said first and second toggle link means; said first and secondguide link means each having first and second ends;

a stationary support means; said first ends of said first and secondguide link means being pivotally mounted to said stationary supportmeans; said second ends of said first and second guide link means beingpivotally connected to said second ends of said first and second togglelink means respectively;

first and second pivotal means pivotally connecting together said secondends of said first and second guide link means respectively, and saidsecond ends of said first and second toggle link means respectively tosaid contact terminal members of said first and second interruptersrespectively;

a spring biasing means having first and second end portions connected tosaid operating shaft and said stationary support means respectively;said operating shaft being movable to move said first and second togglelink means from an interrupter closed position in which said first andsecond toggle link means are extended to an interrupter open position inwhich said first and second toggle link means are collapsed from theirextended position;

and first and second conductive links for connecting said first andsecond vacuum interrupters in series with one another; said first andsecond conductive links each having a first end mechanically andelectrically pivotally connected to said stationary support means, andeach having a second end mechanically and electrically pivotallyconnected to said contact terminal members of said first and secondinterrupters respectively; said first and second conductive linksgenerally forming parallelogram mechanisms with said first and secondguide link means respectively for guiding the motion of said contactterminal members in a straight line; said stationary support meansconsisting of electrically conductive material.

2. The operating mechanism of claim 1 which further includes a guidemeans having an elongated slot extending parallel to the direction ofmovement of said shaft; said operating shaft and said first and secondtoggle link means having a common pivot pin extending therefrom anddisposed within said elongated 'slot for movement therein.

3. The operating mechanism of claim 1 which further includes first andsecond spring bracket means connected to said contact terminal membersof said first and second vacuum interrupters respectively, and whereinsaid spring biasing means includes compression springs disposed betweensaid first and second spring bracket means and said first and secondpivotal means.

4. The operating mechanism of claim 3 wherein said first and secondpivotal means connected to said first and second spring bracket meansrespectively, includes lost motion means whereby the toggle formed bysaid first and second toggle link means can collapse for a givendistance from their fully extended position before said contact terminalmembers are directly mechanically engaged by impact force from saidoperating shaft.

5. The operating mechanism of claim 4 which further includes positionadjustment shim means disposed between said first and second springbracket means and said contact terminal members of said first and secondvacuum interrupters respectively.

6. The operating mechanism of claim 1 which further includesaccelerating spring means connected to said operating shaft for biasingsaid operating shaft toward an interrupter opening position; andtime-delay dashpot means connected to said accelerating spring means fordamping the opening movement of said first and second toggle link meansas they reach the end of their movement to a collapsed position.

1. An operating mechanism for first and second vacuum interrupters; said first and second vacuum interrupters each including generally cylindrical housings having axially disposed and axially movable contact terminal members extending from one end surface thereof; and means for supporting said first and second vacuum interrupters in spaced coaxial relation with said one end surfaces facing one another; said operating mechanism comprising, in combination: an axially movable operating shaft movable generally perpendicular to the axes of said first and second interrupters; first and second toggle link means, each having first and second ends, and pivotally connected at their said first ends to one another and to said operating shaft; first and second guide link means for guiding the motion of said second ends of said first and second toggle link means; said first and second guide link means each having first and second ends; a stationary support means; said first ends of said first and second guide link means being pivotally mounted to said stationary support means; said second ends of said first and second guide link means being pivotally connected to said second ends of said first and second toggle link means respectively; first and second pivotal means pivotally connecting together said second ends of said first and second guide link means respectively, and said second ends of said first and second toggle link means respectively to said contact terminal members of said first and second interrupters respectively; a spring biasing means having first and second end portions connected to said operating shaft and said stationary support means respectively; said operating shaft being movable to move said first and second toggle link means from an interrupter closed position in which said first and second toggle link means are extended to an interrupter open position in which said first and second toggle link means are collapsed from their extended position; and first and second conductive links for connecting said first and second vacuum interrupters in series with one another; said first and second conductive links each having a first end mechanically and electrically pivotally connected to said stationary support means, and each having a second end mechanically and electrically pivotally connected to said contact terminal members of said first and second interrupters respectively; said first and second conductive links generally forming parallelogram mechanisms with said first and second guide link means respectively for guiding the motion of said contact terminal members in a straight line; said stationary support means consisting of electrically conductive material.
 2. The operating mechanism of claim 1 which further includes a guide means having an elongated slot extending parallel to the direction of movement of said shaft; said operating shaft and said first and second toggle link means having a common pivot pin extending therefrom and disposed within said elongated slot for movement therein.
 3. The operating mechanism of claim 1 which further includes first and second spring bracket means connected to said contact terminal members of said first and second vacuum interrupters respectively, and wherein said spring biasing means includes compRession springs disposed between said first and second spring bracket means and said first and second pivotal means.
 4. The operating mechanism of claim 3 wherein said first and second pivotal means connected to said first and second spring bracket means respectively, includes lost motion means whereby the toggle formed by said first and second toggle link means can collapse for a given distance from their fully extended position before said contact terminal members are directly mechanically engaged by impact force from said operating shaft.
 5. The operating mechanism of claim 4 which further includes position adjustment shim means disposed between said first and second spring bracket means and said contact terminal members of said first and second vacuum interrupters respectively.
 6. The operating mechanism of claim 1 which further includes accelerating spring means connected to said operating shaft for biasing said operating shaft toward an interrupter opening position; and time-delay dashpot means connected to said accelerating spring means for damping the opening movement of said first and second toggle link means as they reach the end of their movement to a collapsed position. 